Divided phase ac synchronous motor controller

ABSTRACT

A divided phase windings circuit includes motor divided phase windings, a power switch circuit comprising at least one power switch and a direct current (DC) supply circuit all at a midpoint of the divided motor phase windings, and a non-collapsing DC power supply component to prevent the DC power supply from collapsing when the at least one power switch is on and conducting. The non-collapsing DC power supply component may include one or more of a tap from the motor divided phase windings electrically connected to the DC power supply, a secondary phase coil winding connected to the DC power supply to power the power supply, one or more resistors between the divided phase windings and the power switch circuit, one or more Zener diodes between the divided phase windings and the power switch circuit, and/or an electrical component to create a voltage drop between the motor divided phase windings and the power switch circuit to prevent the power supply from collapsing when the at least one power switch in the power switch circuit is on and conducting.

RELATED APPLICATIONS

This application claims priority to U.S. patent application Ser. No.61/726,550, entitled Divided Phase AC Synchronous Motor Controller, andfiled Nov. 14, 2012, the entire contents of which are incorporatedherein by reference.

FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable.

COMPACT DISK APPENDIX

Not Applicable.

BACKGROUND

In view of the growing proliferation of environmentally friendly laws,enhancements to various classes of motors are required. For example,refrigeration fan motors in a low wattage range, e.g. 4 to 16 watts,used in both the commercial and residential refrigeration markets, havetraditionally been low efficiency, such as around 12%-26% efficient. Itwould be desirable to provide technologies to address enhancementsrequired in different classes of motors.

SUMMARY

A divided phase windings circuit includes motor divided phase windings,a power switch circuit comprising at least one power switch and a directcurrent (DC) supply circuit all at a midpoint of the divided motor phasewindings, and a non-collapsing DC power supply component to prevent theDC power supply from collapsing when the at least one power switch is onand conducting. The non-collapsing DC power supply component may includeone or more of a tap from the motor divided phase windings electricallyconnected to the DC power supply, a secondary phase coil windingconnected to the DC power supply to power the power supply, one or moreresistors between the divided phase windings and the power switchcircuit, one or more Zener diodes between the divided phase windings andthe power switch circuit, and/or an electrical component to create avoltage drop between the motor divided phase windings and the powerswitch circuit to prevent the power supply from collapsing when the atleast one power switch in the power switch circuit is on and conducting.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts motor phase windings divided with a control circuitlocated at a mid-point in the motor phase windings.

FIG. 2 depicts a single phase electronically commutated motor (ECM).

FIG. 3 depicts a divided phase winding circuit.

FIG. 4 depicts a divided phase winding circuit with a tap from thedivided phase winding coil to the direct current (DC) power supply.

FIG. 5 depicts a divided phase winding circuit with resisters betweenthe divided phase windings and the power switch(es).

FIG. 6 depicts a divided phase winding circuit with a secondary coil.

FIG. 7 depicts a control of phase current direction during start up andcontinuous operation below synchronous speeds in a divided phase windingcircuit.

FIG. 8 depicts a control of phase current direction at a synchronousspeed of 1800 revolutions per minute (RPM) in a four pole divided phasewinding circuit.

FIG. 9 depicts a control of phase current direction at a synchronousspeed of 3600 revolutions per minute (RPM) in a two pole divided phasewinding circuit.

FIG. 10 depicts DC supply storage capacitor charging periods.

FIG. 11 depicts a divided phase winding circuit with a secondary coiland one power switch.

FIG. 12 depicts a divided phase winding circuit with a secondary coiland one power switch.

FIGS. 13 and 13A depict a divided phase winding circuit with a secondarycoil and one power switch.

FIG. 14 depicts a divided phase winding circuit with two power switches.

FIG. 15 depicts a divided phase winding circuit with one power switch.

FIG. 16 depicts a divided phase winding circuit with two power switchesin series.

FIG. 17 depicts a divided phase winding circuit with a tap from thedivided phase winding coil to the direct current (DC) power supply andtwo power switches in series.

FIG. 18 depicts a divided phase winding circuit with two power switchesin parallel.

FIG. 19 depicts a divided phase winding circuit with a tap from thedivided phase winding coil to the direct current (DC) power supply andtwo power switches in parallel.

FIG. 20 depicts a motor with a divided phase winding circuit having aprimary AC phase winding and secondary winding to create anon-collapsing DC power supply.

FIG. 21 depicts a motor with a divided phase winding circuit having aprimary AC phase winding and secondary winding to create anon-collapsing DC power supply wound on only one pole.

FIG. 22 depicts a motor with a divided phase winding circuit with atapped primary phase winding to create a non-collapsing DC power supply.

FIG. 23 depicts a motor with a divided phase winding circuit withresisters to create a non-collapsing DC power supply.

FIG. 24 depicts a motor with a divided phase winding circuit with Zenerdiodes to create a non-collapsing DC power supply.

DETAILED DESCRIPTION

New and useful circuits are disclosed that provide advantages over theprior art for controlling synchronous brushless permanent magnet motors.One embodiment of the present disclosure includes one or more circuitsfor an electronically commutated motor (ECM). Another embodiment of thepresent disclosure includes one or more circuits for a shaded polemotor. In one aspect, a motor has multiple motor phases (i.e. motorphase windings) and a supply line voltage through the phases. The motorphases are divided in half and both the motor controller for the motorand the power electronics for the motor are placed at a “mid-point” or“center point” in the supply line voltage between the divided phases.The direct current (DC) power supply (e.g. for the electronics used inthe motor controller) are also located between the divided phases. Themotor phases provide current limiting and the voltage drop from the linevoltage supply lines to low voltage DC to the DC power supply, therebyreducing the DC power supply component count and allowing for the use oflow voltage components for the DC power supply and for the motorcontroller.

Prior systems used a Zener diode or other voltage regulator located inseries with a power switch and the motor phases, which limited themaximum power of the motor to the maximum wattage value of the Zenerdiode. Circuits in the present disclosure eliminate the Zener diodevoltage regulator from the primary current path for the motor phases sothat a Zener diode voltage regulator is not located in series with apower switch and the motor phases, which eliminates the need to lowerthe wattage specification otherwise needed for a Zener diode. Instead,the Zener diode or other voltage regulator is located in parallel withthe power switch(es) in some embodiments of the present disclosure.

Circuits in the present disclosure eliminate the need for anopto-isolator to allow switching between sensing/control electronics ofa motor controller and a power switch of the motor controller. Priorsystems had two neutral reference values, one for sensing/controlelectronics and one for a power switch.

Circuits in the present disclosure have improved line phase angledetection, eliminating the need for a precision resistance bridge linkedto the input of an opto-isolator. Thus, the circuits of this aspect havemore accurate line phase angle detection.

Circuits in the present disclosure reduce different electrical neutralvalues for the power switches and motor controller to one value. Thisguarantees that the power switch(s) of the circuits with this aspectwill reliably transition from completely “off” to fully saturated.

Prior systems that included two switches have a difficult time turningone switch off completely for one half of an AC cycle. Circuits in thepresent disclosure place one or more switches outside of a DC powersupply and motor controller circuit, resulting in proper switching.

Each of these improvements not only increases the reliability of theoperation of the motor controller, but also serves to improve thecombined motor/motor controller efficiency.

The divided phase winding circuits in the present disclosure can be usedin a variety of motors, such as DC brushless motors/electronicallycommunicated motors (ECMs), shaded pole motors, other synchronousmotors, permanent-split capacitor (PSC) motors, etc.

For example, FIG. 1 depicts a motor with divided motor phase windingsand a motor control circuit located at a mid-point in the divided motorphase windings. The motor includes stator and a rotor mounted on ashaft. The rotor is mounted for rotation in a core structure, such aslaminated core structure or other core structure. The rotor has a bodyportion which is shown as cylindrical in shape. Around the periphery ofthe body are located arcuately shaped permanent magnetic portions. Themagnetic portion has its north magnetic pole adjacent to the outersurface of the rotor and the magnetic portion has its south magneticpole located adjacent to outer periphery of the rotor. A winding or pairof windings are mounted on the connecting portion 3A of the corestructure. The motor also includes a Hall Effect switching device, aportion of which extends to adjacent the periphery of the rotor forresponding to the magnetic polarity of the respective rotor magneticportions. In the construction as shown, the Hall Effect switch islocated adjacent the outer periphery of the magnetic portion during halfof each revolution of rotor and adjacent the outer periphery of themagnetic portion during the remaining half of each revolution of rotor.

The motor can operate below, at, or above synchronous speeds. This isdue to the fact that fractions of half cycles can flow through the phasewindings.

The divided phase winding circuit of FIG. 1 includes input connectionson leads L1 and L2 connected to a source of alternating current (AC)energy during operation, such as AC line voltage. The leads L1 and L2are connected across a series circuit that includes divided phasewindings shown connected in series across a control circuit. Forexample, the control circuit may include a full wave diode rectifierbridge circuit connected in series to the divided phase windings and apower switch(es) circuit having one or more switches or other powercontrollable switching devices connected to the output of the full wavediode rectifier bridge circuit.

The divided phase windings can be bifilar or lap wound. The alternatingcurrent power source has its lead L1 connected to the start side S1 ofthe winding. The other end of the winding, labeled F1, is connected toone of the inputs of the control circuit. The other input side of thecontrol circuit is attached to the start side S2 of the second dividedphase winding and the finish side of the same divided phase winding,labeled F2, is attached to the input lead L2 of the AC power source.

As another example, FIG. 2 depicts a single phase ECM in which the motorphase windings are divided and a motor controller (motor controlcircuit) is located at a mid-point in the divided motor phase windings.

FIG. 3 discloses a divided phase winding circuit for dividing motorphase windings (also referred to as motor phases or phase coils herein)of a motor in half and placing both a motor controller for the motor andpower electronics for the motor, including the DC power supply and apower switch(es) circuit with one or more power switches, at a“mid-point” or “center point” in the supply line voltage between thedivided phases. In the example of FIG. 3, the motor phase winding isdivided in half. Some variation from the half division is allowable,such as between zero and plus/minus 20% of the halfway point.

The divided phase winding circuit of FIG. 3 includes two divided phasewindings, each connected to AC line voltage L1 and L2 respectively. A DCpower supply is electrically connected to the divided phase windings,such as at the finish side of the first phase winding and the start sideof the second phase winding. The divided phase winding operates to lowerthe AC line voltage to a voltage compatible with the DC power supply.Thus, the number of windings in the divided phase winding can beselected to reduce the AC line voltage received at L1 and L2 to aselected lower voltage to be received by the DC power supply. Thedivided phase winding also operated to filter noise from the AC linevoltage received at L1 and L2.

The DC power supply converts the low voltage AC power received from thedivided phase windings to a DC voltage configured to power the DCpowered components of the divided phase winding circuit, including themotor controller. The DC power supply then supplies power to the motorcontroller.

The motor controller controls the start-up and operation of the dividedphase winding circuit. For example, the motor controller controlsstart-up, including where the motor is a synchronous motor. The motorcontroller determines the location of the rotor relative to the stator.The motor controller also determines and monitors the speed of therotor, such as in revolutions per minute (RPMs), to determineoperational parameters of the motor, such as when the motor has reachedsynchronous speed, and controls the motor based on the location of therotor and or speed of the motor. In one example, the motor controllerhas a Hall effect switch and/or other rotation determining device todetermine the position of the rotor and/or rotation counting or speeddetermining device to determine the speed of the rotor.

The power switch(es) circuit includes one or more power switches, suchas one or more metal-oxide-semiconductor field-effect transistors(MOSFETs), silicon-controlled rectifiers (SCRs), transistors, or otherswitches or switching devices. The one or more switches are one or offor one is on while the other is off. For example, in one half cycle ofan AC cycle, a first power switch is on and conducting while the secondswitch is off and not conducting. In the other half cycle of the ACcycle, the second power switch is on and conducting while the firstswitch is off and not conducting. In circuits with one switch, theswitch may be on and conducting or off and not conducting during one ormore portions of the AC cycle.

The power switch(es) circuit is isolated from (outside of) the DC powersupply, which makes the divided phase winding circuit more stable thancircuits having the power switch(es) circuit within (and not isolatedfrom) the DC power supply.

Normally, when the power switch(es) of a circuit turn on, there is onlya slight voltage drop through the power switch(es) due to the minorresistance of the power switch(es). Therefore, if the input voltage forthe DC power supply is developed by connecting the DC power supply leadsto both sides of a power switch (or power switches), this would resultin the DC power supply collapsing when the power switch is in an ‘on’state or not being able to receive power and power the DC components ofthe circuit. The divided phase winding circuit includes one or morenon-collapsing DC power supply components, including voltage dropcomponents or direct DC power supply powering components to create anon-collapsing DC power supply. Examples of non-collapsing DC powersupply components include a tap from the primary phase windingelectrically connected to the DC power supply, a secondary phase coilwinding connected to the DC power supply to power the power supply,resistors between the divided phase windings and the power switch(es)circuit, one or more Zener diodes between the divided phase windings andthe power switch(es) circuit, or other components to create a voltagedrop between the primary divided phase windings and the power switch(es)circuit to prevent the power supply from collapsing when the powerswitch(es) in the power switch(es) circuit is/are on and conducting. Thedivided phase winding circuit therefore provides a constant flow ofpower regardless of whether the power switch(es) circuit is on andconducting or off and not conducting.

Many electronically controlled synchronous motors have circuits thatdetect the zero crossing of the AC voltage applied to the phasewindings. This zero crossing detection circuit sends a signal to themotor controller to determine when the motor is at synchronous speed. Ifthe AC supply voltage has electrical noise riding on, usually due toother equipment operating on the same circuit, this electrical noise cancause the zero crossing detector to operate incorrectly affecting thecontrol of the motor which normally appears as acoustical noise in themotor.

In one example, the divided phase winding circuit is part of asynchronous motor. The synchronous motor receives line power (that is,AC power) at L1 and L2. In a synchronous motor using a divided phasewinding using the associated circuit of the present disclosure does notrely upon detecting the zero crossing of the applied AC voltage tocontrol the motor but rather detects the polarity of the voltage i.e.whether the polarity L2 is higher or less than L1 allowing for quietoperation even when electrical noise is present in the AC supply.

The DC power supply in FIG. 3 is electrically connected directly to thedivided phase windings. Thus, the DC power supply is powered by thedivided phase windings regardless of the status of the power switch(es)circuit.

FIG. 4 discloses another divided phase winding circuit for dividingmotor phase windings of a motor in half and placing both a motorcontroller for the motor and power electronics for the motor, includingthe DC power supply and a power switch(es) circuit with one or morepower switches, at a “mid-point” or “center point” in the supply linevoltage between the divided phases. The divided phase winding circuit ofFIG. 4 includes a tap from the primary divided phase windingelectrically connected to the DC power supply to create a non-collapsingDC power supply.

In some circuits, when the motor reaches synchronous speed, the one ormore power switch(es) turn off and thereby cause the low voltage powerto stop flowing to the motor controller. In one example, the path fromone divided phase winding through the power switch(es) to anotherdivided phase winding is shorted, such as at synchronous speed,resulting the DC power supply and motor controller no longer receivingthe low power supply voltage from the phase windings, such as in theevent there is no capacitor to hold a charge during the short or acapacitor that is present is not large enough to hold enough chargeduring the short. The circuit of FIG. 4 includes a tap from the coils ofthe phase windings to the DC power supply so that the low voltage powersupply flows directly from the phase windings to the DC power supply,bypassing the power switch(es) (“divided motor phase controller”). Thecircuit of FIG. 4 thereby guarantees that the low voltage power supplyis supplied to the DC power supply, for example at synchronous speed.

In one example, a DC power supply for a divided motor phase controlleris formed by a Zener diode and a storage capacitor that receives powerduring a portion of an alternating current (AC) cycle when the powerswitch(es) are off. When the motor is operating at synchronous speed,the power switch(es) are continuously conducting. Therefore, the amountof voltage being supplied to the DC power supply is equal to the voltagedrop across the switch(es), which can result in a low voltage when usinglow on resistance (RDS(on)) power MOSFETs.

FIG. 5 discloses another divided phase winding circuit for dividingmotor phase windings of a motor in half and placing both a motorcontroller for the motor and power electronics for the motor, includingthe DC power supply and a power switch(es) circuit with one or morepower switches, at a “mid-point” or “center point” in the supply linevoltage between the divided phases. The circuit of FIG. 5 includesresistors R1 and R2 between the motor phase windings and the powerswitch(es) to hold up and therefore maintain the low voltage powersupply supplied from the phase windings to the DC power supply andcreate a non-collapsing DC power supply. The circuit of FIG. 5 therebymaintains the low voltage power supply to the DC power supply, forexample at synchronous speed.

FIG. 6 discloses another divided phase winding circuit for dividingmotor phase windings of a motor in half and placing both a motorcontroller for the motor and power electronics for the motor, includingthe DC power supply and a power switch(es) circuit with one or morepower switches, at a “mid-point” or “center point” in the supply linevoltage between the divided phases. The primary divided phase windinglimits the current that can flow to the DC power supply eliminating theneed for current limiting components that waste power. The divided phasewinding circuit of FIG. 6 includes a secondary phase windingelectrically connected to the DC power supply to create a non-collapsingDC power supply.

In one example, the power switch(es) circuit includes a Zener diode orother voltage regulator and a power switch in parallel. Whereas, priorsystems included the power circuit in series with other components.Because the power switch is in parallel with the Zener diode and not inseries, it can always be on. However, if the power switch is off,current can still flow through the Zener diode.

The circuit of FIG. 6 includes one or more secondary coils (alsoreferred to as a secondary winding) that provide a low voltage powersupply to the DC power supply, such as when the motor is at start-up.The one or more secondary coils also act as a high frequency noisefilter to filter out high frequency noise from the low power voltagesupplied to the DC power supply.

The secondary winding may be distributed anywhere, such as evenlybetween the first and second divided phase windings, all on one pole, orunevenly between the first and second divided phase windings, such as agreater number of turns or coils on one secondary winding than anothersecondary winding.

In the example of FIG. 6, the divided phase winding circuit can turn offthe DC electronics, including the motor controller, when the motor is onand at synchronous speed. Thus, the motor controller of the dividedphase winding circuit determines the speed of the motor and whether themotor is or is not at synchronous speed. For example, 1800 RPM may bethe synchronous speed for a motor with four stator poles (two northstator poles and two south stator poles). Every half AC cycle, power issupplied to one of the magnetic poles. Therefore, it takes two cycles toprovide power to the four magnetic poles. Thus, the synchronous speed is1800 RPM if the motor is synced to line AC. Similarly, the synchronousspeed for an eight-pole stator would be 900 RPMs.

FIG. 7 depicts a control of phase current direction during start up andcontinuous operation below synchronous speeds in a divided phase windingcircuit.

As shown in FIG. 7, the current will always flow across both dividedphase windings and control circuit in the same direction. The dividedphase windings, being in series with the control circuit, represent onewinding with the control circuit placed at the mid-point or center pointbetween the divided phase windings. The current and voltage applied tothe divided phase windings will always be in the same direction throughboth coils, and the magnetic polarity of the divided phase windings willlikewise be the same.

As discussed below, the control circuit may include a diode rectifierbridge circuit whose output is connected to one or more power switches.As shown in FIG. 7, if the output terminals of the diode bridgerectifier of the control circuit are shorted when the voltage on lead L1is positive the current will only flow through the winding 102 and 104in one direction, but in half cycle increments. If the voltage acrossleads L1 and L2 is 60 cycles, then the outputs of the diode bridgerectifier circuit in the control circuit will be shorted only when leadL1 is positive, and current flow will flow only in one direction and for8 milliseconds. No current will flow for 8 milliseconds on the alternatehalf cycles. Then current would flow for another 8 milliseconds and soon. If the output of the diode bridge circuit of the control circuit isshorted when lead L2 is positive, then power will flow in exactly thesame manner. If the shorting of the output of the bridge is accomplishedselectively, that is based on the angular position of the magneticrotor, continuous motor action will be produced. If the diode bridgerectifier circuit output in the control circuit is shorted for afraction of a half cycle selectively based on the angular position ofthe magnetic rotor as described above, and only when lead L1 ispositive, then any desired speed can be accomplished including speedshigher than the synchronous speed. The characteristics of such a motorwould be similar to a DC motor with pulsating current applied to theinputs. However, rather than having multiple power switching componentsachieve the switching of the divided phase windings, the divided phasewinding circuit makes use of the fact that alternating current inconjunction with one power switching component can accomplish theswitching.

FIG. 8 depicts an example of control of phase current direction at asynchronous speed of 1800 revolutions per minute (RPM) in a four poledivided phase winding circuit. At synchronous speed, the controlledphase is synchronized with the AC line input.

FIG. 9 depicts a control of phase current direction at a synchronousspeed of 3600 revolutions per minute (RPM) in a two pole divided phasewinding circuit. At synchronous speed, the controlled phase issynchronized with the AC line input.

FIG. 10 depicts an example of DC power supply storage capacitor chargingperiods in a divided phase winding circuit. Note the correlation to thewave form of FIG. 7.

FIG. 11 depicts a divided phase winding circuit with a secondary coiland one power switch. The primary divided phase winding limits thecurrent that can flow to the DC power supply.

The motor controller controls switching for the power switch(es) circuitbased on timing of the input frequency and rotor position. The motorcontroller controls the start-up and operation of the divided phasewinding circuit. For example, the motor controller controls start-up,including where the motor is a synchronous motor. The motor controllerdetermines the location of the rotor relative to the stator. The motorcontroller also determines and monitors the speed of the rotor, such asin revolutions per minute (RPMs), to determine operational parameters ofthe motor, such as when the motor has reached synchronous speed, andcontrols the motor based on the location of the rotor and or speed ofthe motor. In one example, the motor controller has a Hall effect switchand/or other rotation determining device to determine the position ofthe rotor and/or rotation counting or speed determining device todetermine the speed of the rotor.

In one example, the power switch(es) circuit includes a Zener diode orother voltage regulator and a power switch in parallel. Whereas, priorsystems included the power circuit in series with other components.Because the power switch is in parallel with the Zener diode and not inseries, it can always be on. However, if the power switch is off,current can still flow through the Zener diode.

The circuit of FIG. 11 includes one or more secondary coils (alsoreferred to as a secondary winding) that provide a low voltage powersupply to the DC power supply, such as when the motor is at start-up.The one or more secondary coils also act as a high frequency noisefilter to filter out high frequency noise from the low power voltagesupplied to the DC power supply.

The secondary winding may be distributed anywhere, such as evenlybetween the first and second divided phase windings, all on one pole, orunevenly between the first and second divided phase windings, such as agreater number of turns or coils on one secondary winding than anothersecondary winding.

The way that the coils are connected to the circuit via the diode bridgerectifier allow for current to flow through the coils in only onedirection at any given time. The improvements that have been made tothis motor and controller greatly improve the DC logic power supplywhich enables a more reliable logic control circuit. Secondary coils arewound with the motor coils in a method that creates a transformer usingthe motor coils as primary.

The improvements that have been made to this motor and controllergreatly improve the DC logic power supply which enables a more reliablelogic control circuit. Secondary coils are wound with the motor coils ina method that creates a transformer using the motor coils as primary.The example of FIG. 11 uses a 20:1 ratio. The example of FIG. 11includes 500 turns per motor primary coil and 25 turns per secondarycoil that are wound on the same stator pole. However, other turn ratiosmay be used, higher or lower. The ratio between the primary motor coilsand secondary coils may change with AC input power and/or DC powerrequirements. This circuit not only isolates all DC circuitry from highvoltages from the line, but also creates a non-collapsible DC powersupply to the control circuit when power is applied to inputs L1 and L2.

The power switch(es) circuit consists of 2 main components, a full wavebridge rectifier BR1 and a MOSFET power switch Q1. The full wave bridgerectifier BR1 guarantees that no negative voltage will be supplied tothe drain (top) of the power switch Q1. The full wave bridge rectifierBR1 also guarantees that no positive voltage will be supplied to thesource (bottom) of the power switch Q1 so that current can only flowfrom the drain to the source of the power switch Q1 when biased by apositive voltage on the gate of the power switch Q1 via resistor R1.Simultaneously, as a positive rectified AC power supply is present atthe drain of the power switch Q1, the power switch Q1 is biased by thesame voltage signal via resistor R1. Diode D5 protects the gate of thepower switch Q1 by guaranteeing that any voltage on the gate of thepower switch Q1 will be greater than −0.7 VDC, as anything less coulddamage or destroy the power switch Q1. Resistor R11 and capacitor C5 areused as a “snubber” to filter out transients or high frequency noise.R11 and C5 provide added protection for the MOSFET power switch Q1,especially in noisy environments.

FIG. 12 depicts a divided phase winding circuit with a secondary coiland one power switch. The circuit of FIG. 12 includes the same powerswitch(es) circuit of FIG. 11 and the same secondary coils. In addition,the motor controller of FIG. 12 includes a logic control circuit tocontrol operation of the motor, including through synchronous speed, alogic control shut off circuit to control when the power switch(es)circuit is turned off, and a non-collapsing DC power supply to supply DCpower to the logic control circuit and login control shut off circuit.The logic control circuit and login control shut off circuit may beconfigured as a single logic control circuit.

In one embodiment, one purpose of this divided phase windings circuit isto allow a motor to run synchronously to the AC power supply linefrequency (for example, for a 4 pole motor, 60 Hz=1800 rpm and 50Hz=1500 rpm). Without any control circuitry, the power switch(es)circuit would allow current to flow as if coil pairs L1 and L2 wereshorted together through the power switch(es) circuit. The controlcircuitry simply turns power switch(es) circuit off until the rotor isin the proper position compared to the line voltage. For this reason, inone aspect, the power switch(es) circuit is rated for the AC powersupply line voltage. The control circuitry components can all be at thelogic level voltage (VCC). Logic power is supplied by secondary coilsthat are wound on the same poles as the primary motor coils. Secondarycoils could be wound on any number of poles as long as the secondarypower meets logic power requirements. Since the control circuit is onlyneeded to start the motor and bring it to synchronous speed, the logiccontrol shut off circuit optionally is included to shut off the maincontrol circuit. The logic control shut off circuit is optional. Byshutting the control circuit off, the power switch(es) circuit willallow full line power to the motor minus any losses in the powerswitch(es) circuit. This will increase total efficiency and the life ofcomponents especially when the motor runs for long periods.

FIGS. 13 and 13A depict a divided phase winding circuit with a secondarycoil and one power switch. The circuit has two AC supply line inputs L1and L2, which are connected to an AC power source during operation ofthe motor.

Power Switch

The Power Switch block consists of 2 main components, a full wave bridgerectifier BR1 and a MOSFET power switch Q1. The full wave bridgerectifier BR1 guarantees that no negative voltage will be supplied tothe drain (top) of the power switch Q1. The full wave bridge rectifierBR1 also guarantees that no positive voltage will be supplied to thesource (bottom) of the power switch Q1 so that current can only flowfrom the drain to the source of the power switch Q1 when biased by apositive voltage on the gate of the power switch Q1 via resistor R1.Simultaneously, as a positive rectified AC power supply is present atthe drain of the power switch Q1, the power switch Q1 is biased by thesame voltage signal via resistor R1. Diode D5 protects the gate of thepower switch Q1 by guaranteeing that any voltage on the gate of thepower switch Q1 will be greater than −0.7 VDC, as anything less coulddamage or destroy the power switch Q1. Resistor R11 and capacitor C5 areused as a “snubber” to filter out transients or high frequency noise.R11 and C5 provide added protection for the MOSFET power switch Q1,especially in noisy environments.

DC Power Supply

As soon as power is applied to the motor and current is flowing throughthe motor phase windings (motor primary coils), there is power on thesecondary windings (secondary coils) in the same manner as the operationof a transformer. The value of voltage on the secondary coils isdirectly proportional to the input voltage and the primary to secondaryturn count ratio. Using the example in FIG. 11, if the input voltage tothe primary coils is 120 VAC and the turn count ratio from primary tosecondary is 20:1, then the voltage on the secondary coils wouldcalculate to approximately 6 VAC minus any losses. Power from thesecondary coils is supplied directly from the secondary coils to the DCpower supply. The full wave bridge rectifier BR2 rectifies the lowvoltage AC power supply from the secondary coils. The full wave bridgerectifier BR2 can be a low power component based on the DC supplyrequirements.

Zener diodes Z1 and Z2 are connected in series with each other anode toanode, and each cathode is connected to the AC power supply inputs ofthe full wave bridge rectifier BR2. This method is used to protect thefull wave bridge rectifier BR2 from AC power supply inputs that couldexceed maximum ratings for the component. The negative output from thefull wave bridge rectifier BR2 is connected to the circuit ground, whichis also connected to the same ground as the power switch block. Thepositive output from the full wave bridge rectifier BR2 is connected tothe low drop-out regulator LDO1 and capacitor C1. Capacitor C1 isprovided to smooth the rectified AC power supply signal going to theinput of the low drop-out regulator LDO1. A bypass capacitor C7 could beused on the output of the low drop-out regulator LDO1 to help reducenoise on the positive DC rail (VCC). Also, a larger capacitor C10 couldbe used on the output of the low drop-out regulator LDO1 to smooth thepositive DC rail and ensure power during some low voltage situations. C7and C10 are not required but are provided to add reliability andprotection for low voltage DC components, especially in a noisyenvironment.

Logic Control

The control circuit controls switching for the power switch(es) circuitbased on timing of the AC supply line input frequency and rotorposition. Timing of the AC supply line input frequency is sensed usingan AC buffer that consists of bi-polar junction transistors (BJTs) Q2and Q3 and diodes D6 and D7. Current to the AC buffer input is limitedby a high value resistor R3. Diode D6 ensures that the AC buffer inputis not greater than the positive DC supply voltage. Diode D7 ensures theAC buffer input is greater than −0.7 volts referenced to the DC supplyground.

When the input to the AC buffer is logic high, BJT Q2 is biased, and theoutput of the AC buffer is also logic high. When the input to the ACbuffer is logic low, BJT Q3 is biased, and the output of the AC bufferis logic low. The output the AC buffer is connected to a filterconsisting of capacitor C6 and resistor R13. The filter is not requiredbut provides protection and reliability in noisy environments.

Rotor magnet polarity is sensed using Hall-effect switch IC1. Though,another switch or sensing device may be used to sense rotor magnetpolarity and/or rotor position and/or determine speed and/or determinerotor revolutions. The Hall-effect switch IC1 is an open-collectoroutput and therefore requires a pull-up to the positive DC rail (VCC).Resistor R2 provides the pull-up required for the open-collector output.

The output of the Hall-effect switch IC1 and the output of the AC bufferare compared using a single circuit logic XOR IC2. The output of the XORIC2 is the difference between the Hall-effect switch IC1 and the ACbuffer, which will bias MOSFET power switch Q1 of the power switch(es)circuit. When the Hall-effect switch IC1 output is logic low, the powerswitch Q1 will only be biased when the AC supply input L1 to the motoris negative. When the output of the Hall-effect switch IC1 is logichigh, the power switch Q1 will only be biased when the AC supply inputL1 to the motor is positive. During motor start up, there can bemultiple input AC cycles where either only the positive or only thenegative inputs from AC supply input L1 will pass through the powerswitch Q1.

Using the power switch Q1, waveforms can be “chopped” or shut off at anytime when the drain and gate voltage of the power switch Q1 is abovebiasing voltage. For example, see FIG. 7. The gate of the power switchQ1 is held logic low when the output of the XOR IC2 is logic high bybiasing BJT Q4. When BJT Q4 is biased, any current flowing from resistorR1 will bypass the gate of the power switch Q1 and flow through BJT Q4from collector to emitter electrically connecting the gate of the powerswitch Q1 to its source and will shut off the power switch Q1immediately.

When the frequency of the Hall-effect switch IC1 matches the frequencyof the input AC supply, the motor is running synchronously. If the motoris running synchronously, the control circuit is not needed until eitherthe motor falls out of sync or the motor is stopped and restarted. Whenthe frequency to voltage regulator IC3 senses synchronous speed orgreater from the Hall-effect switch IC1, the output of the XOR IC2 isheld logic low via the open-collector output of the voltage regulatorIC3. If the sensor speed is less than that of the input AC supply, theopen-collector output of the voltage regulator IC3 is off, which willleave the output of the XOR IC2 unaffected.

This method ensures that when the motor is running at a synchronousspeed, the power switch Q1 is not shut off by the logic control. But, ifthe motor slows down below synchronous speeds, then the logic controllerwill control the motor timing as it does for start-up. Using this methodimproves overall motor efficiency and the expected lifetime ofcomponents in the circuit.

External components are required to set timing for the voltage regulatorIC3. Resistors R4, R5, R6 and R7 may be 1% tolerance so that the voltageregulator IC3 operates within accurate parameters. Capacitor C1 operatesin conjunction with the resistors R6 and R7 to set the frequency atwhich the open-collector output of the voltage regulator IC3 will turnon. Capacitor C3 is used for an internal charge pump in the voltageregulator IC3. Capacitor C4 is used to AC couple the input to thevoltage regulator IC3 since the voltage regulator IC3 will only detectfrequencies that have a zero-voltage crossing. Resistor R8 limitscurrent to the AC couple C4 at the input of the voltage regulator IC3.

FIG. 14 depicts a divided phase winding circuit with two power switches.

FIG. 15 depicts a divided phase winding circuit with one power switch.

FIG. 16 depicts a divided phase winding circuit with two power switchesin series. Diodes D1 & D2 are 1N4003 and diodes D3 & D4 are 1N914.Transistors Q3 and Q4 are 2N3904. IC1 is a Hall-effect switch/sensor.Diodes D5 and D6 are used to increase the current capacity for theinternal diodes in switches Q1 and Q2 (d1 & d2) if the phase currentexceeds the internal diodes forward current rating. Capacitors C2 and C3are optional in one embodiment. Capacitors C2 and C3 are used to createa ‘turn on’ delay for switches Q1 and Q2 to add additional charge timefor capacitor C1 if necessary to insure a solid 3.3 VDC or 5 VDC supplyfor Hall switch/sensor IC1, depending upon the device choice for Hallswitch/sensor IC1. In prior systems, 5 VDC was necessary to switch onthe logic level power MOSFET switch.

Diodes D1, D2, d1, and d2 perform the rectification of the AC power forthe DC power supply for Hall switch/sensor IC1.

Zener diode ZD1 provides the voltage regulator for the Hallswitch/sensor IC1's DC supply.

RL provides current limiting for the DC power supply. It should be setto approximately limit the current to 10 mA. The Hall switch/sensor IC1uses 6 mA, including the base drive current for the internal opencollector output transistor. Additional DC current will be used toswitch Q3 and is supplied through the ‘pull up’ resistor R3. Thecollector to emitter current for switch Q3 and the base and collector toemitter current for switch Q4 is not supplied by the DC power supply butis supplied by the current through the motor phase windings. It ispreferable to assure that transistors Q3 and Q4 turn completely ‘off’ atthe proper times. It is preferred in one embodiment, but not arequirement, that the switches turn fully ‘on’ or in saturation at theproper times for maximum operational efficiency.

FIG. 17 depicts a divided phase winding circuit with a tap from thedivided phase winding coil to the direct current (DC) power supply andtwo power switches in series.

FIG. 18 depicts a divided phase winding circuit with two power switchesin parallel.

FIG. 19 depicts a divided phase winding circuit with a tap from thedivided phase winding coil to the direct current (DC) power supply andtwo power switches in parallel.

FIG. 20 depicts a motor with a divided phase winding circuit having aprimary AC phase winding and secondary winding to create anon-collapsing DC power supply. In the motor of FIG. 20, the secondarywinding is wound on all poles. However, the secondary winding can bewound on just one pole, two poles, three poles, or another number ofpoles. The secondary winding is connected in series with the primaryphase winding in the motor of FIG. 20. However, the secondary windingalso may be connected in parallel or with a combination of both seriesand parallel. The motor of FIG. 20 is a four pole permanent magnetsynchronous motor. The synchronous speed for the motor when operating at60 Hz AC is 1800 RPM.

FIG. 21 depicts a motor with a divided phase winding circuit having aprimary AC phase winding and secondary winding to create anon-collapsing DC power supply wound on only one pole. The motor of FIG.21 is a four pole permanent magnet synchronous motor. The synchronousspeed for the motor when operating at 60 Hz AC is 1800 RPM.

FIG. 22 depicts a motor with a divided phase winding circuit with atapped primary phase winding to create a non-collapsing DC power supply.The motor of FIG. 22 is a four pole permanent magnet synchronous motor.The synchronous speed for the motor when operating at 60 Hz AC is 1800RPM.

The motor has a stator with 4 poles and a rotor with 4 magnets N, S, N,S facing the stator. The motor has a shaft (center circle) and rotorback iron (the area between the shaft and the magnets). The primarydivided phase windings care connected to an AC power supply at L1 andL2, respectively. A secondary winding is connected to the DC powersupply.

FIG. 23 depicts a motor with a divided phase winding circuit withresisters between the divided phase windings and the power switch(es)circuit to create a non-collapsing DC power supply. The motor of FIG. 23is a four pole permanent magnet synchronous motor. The synchronous speedfor the motor when operating at 60 Hz AC is 1800 RPM.

FIG. 24 depicts a motor with a divided phase winding circuit with Zenerdiodes between the divided phase windings and the power switch(es)circuit to create a non-collapsing DC power supply. The motor of FIG. 24is a four pole permanent magnet synchronous motor. The synchronous speedfor the motor when operating at 60 Hz AC is 1800 RPM.

Those skilled in the art will appreciate that variations from thespecific embodiments disclosed above are contemplated by the invention.The invention should not be restricted to the above embodiments, butshould be measured by the following claims.

What is claimed is:
 1. A circuit comprising: motor divided phasewindings; a power switch circuit comprising at least one power switchand a direct current (DC) supply circuit all at a midpoint of thedivided motor phase windings; and a non-collapsing DC power supplycomponent to prevent the DC power supply from collapsing when the atleast one power switch is on and conducting.
 2. The circuit of claim 1wherein the non-collapsing DC power supply component comprises at leastone member of a group consisting of a tap from the motor divided phasewindings electrically connected to the DC power supply, a secondaryphase coil winding connected to the DC power supply to power the powersupply, one or more resistors between the divided phase windings and thepower switch circuit, and one or more Zener diodes between the dividedphase windings and the power switch circuit.
 3. The circuit of claim 1wherein the non-collapsing DC power supply component comprises anelectrical component to create a voltage drop between the motor dividedphase windings and the power switch circuit to prevent the power supplyfrom collapsing when the at least one power switch in the power switchcircuit is on and conducting.